Method of Making Vapor Deposited Oxygen-Scavenging Particles

ABSTRACT

This invention discloses a method of making an oxygen scavenging particle comprised of an activating component and an oxidizable component wherein one component is deposited upon the other component from a vapour phase and is particularly useful when the activating component is a protic solvent hydrolysable halogen compound and the oxygen scavenging particle is a reduced metal.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application claims the benefit of the priority of U.S.Provisional Patent Application Ser. No. 60/601,268 filed 13 Aug. 2004and U.S. patent application Ser. No. 11196552, filed on 3 Aug. 2005, allthe teachings of which are incorporated herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to oxygen scavenging particles and manufacturingmethods thereof having utility in packaging, particularly suitable forincorporation into film-forming polymers, preferably aromatic polyesterresins and the wall of a container made from the aromatic polyestercontaining the scavenging particle.

2. Description of Related Art

Products sensitive to oxygen, particularly foods, beverages andmedicines, deteriorate or spoil in the presence of oxygen. One approachto reducing these difficulties is to package such products in acontainer comprising at least one layer of a so-called “passive” gasbarrier film that acts as a physical barrier and reduces or eliminatesthe transmission of oxygen through the container wall but does not reactwith oxygen.

Another approach to achieving or maintaining a low oxygen environmentinside a package is to use a packet containing a rapid oxygen absorbentmaterial. The packet, also referred to as a pouch or sachet, is placedin the interior of the package along with the product. The oxygenabsorbent material in the sachet protects the packaged product byreacting with the oxygen before the oxygen reacts with the packagedproduct.

Although oxygen absorbents or scavenger materials used in packets reactchemically with the oxygen in the package, they do not prevent externaloxygen from penetrating into the package. Therefore, it is common forpackaging using such packets to include additional protection such aswrappings of passive barrier films of the type described above. Thisadds to product costs.

In view of the packet or sachet's disadvantages and limitations, it hasbeen proposed to incorporate an “active” oxygen absorbent, i.e. one thatreacts with oxygen, directly into the walls of a packaging article.Because such a packaging article is formulated to include a materialthat reacts with the oxygen permeating through its walls, the package issaid to provide an “active-barrier” as distinguished from a passivebarrier that merely blocks the transmission of oxygen but does not reactwith it. Active-barrier packaging is an attractive way to protectoxygen-sensitive products because it not only prevents oxygen fromreaching the product from the outside, it can also absorb oxygen presentwithin a container wall, and absorb the oxygen introduced during thefilling of the container.

One approach for obtaining active-barrier packaging is to incorporate amixture of an oxidizable metal (e.g., iron) and an activating componentwhich promotes the reaction of the metal with oxygen, often in thepresence of water, into a suitable film-forming polymer. Examples ofactivating components are electrolytes (e.g., sodium chloride),acidifying components, electrolytic acidifying components, or proticsolvent hydrolysable halogen compounds like Lewis acids (e.g. aluminumchloride). In the case of nano-metals, little or no activating componentmay be needed due their inherent pyrophoricity.

The scavenger containing film forming polymer is then melt processedinto a monolayer or multilayer article such as a preform, bottle, sheetor film that eventually forms the resulting oxygen scavenger-containingwall or walls of the rigid or flexible container or other packagingarticle. It will be understood that a film-forming polymer is one thatis capable of being made into a film or sheet. The present invention isnot, however, limited to films and sheets. Examples of such film formingpolymers are polyamides, polyethylenes, polypropylenes, and polyesters.

The container of the present invention also includes bottle walls,trays, container bases, or lids. It should be appreciated thatreferences to the container sidewall and container wall also refer tothe lid, bottom and top sides of the container, and a film that may bewrapped around the product such as meat wraps.

One difficulty with scavenger systems incorporating an oxidizable metalor metal compound and an electrolyte into a thermoplastic layer is theinefficiency of the oxidation reaction. High loading of scavengercompositions and relatively large amounts of electrolyte are often usedto obtain sufficient oxygen absorption scavenging rate and capacity inactive-barrier packaging.

According to U.S. Pat. No. 5,744,056, oxygen-scavenging compositionsthat exhibit improved oxygen-absorption efficiency relative to systemssuch as iron and the electrolyte sodium chloride are obtainable byincluding a non-electrolytic, acidifying component in the composition.In the presence of moisture, the combination of the electrolyte and theacidifying component promotes the reactivity of metal with oxygen to agreater extent than does either alone. However, the acidifying componentwhen used alone does not exhibit sufficient oxygen-scavengingproperties.

A particularly preferred oxygen-scavenging composition according to theU.S. Pat. No. 5,744,013 comprises iron powder, sodium chloride andsodium acid pyrophosphate, in amounts from about 10 to 150 parts byweight of sodium chloride plus sodium acid pyrophosphate per hundredparts by weight iron.

These conventional scavenging compositions are created by dry blendingthe ingredients or depositing the acidifying agents and salts onto themetal particle out of an aqueous liquid or slurry and then regrindingthe composition, thus creating more particles.

U.S. Pat. No. 5,744,056 teaches that the degree of mixing of theoxidizable metal, electrolyte and acidifying components and, if used,optional binder component has been found to affect oxygen absorptionperformance of the oxygen-scavenging compositions, with better mixingleading to better performance. Mixing effects are most noticeable at lowelectrolyte plus acidifying components to oxidizable metal componentratios and at very low and very high acidifying component to electrolytecomponent ratios. Below about 10 parts by weight electrolyte plusacidifying components per hundred parts by weight metal component, orwhen the weight ratio of either the electrolyte or acidifying componentto the other is less than about 10:90, the oxygen scavenger componentsare preferably mixed by aqueous slurry mixing followed by oven dryingand grinding into fine particles. Below these ratios, mixing bytechniques suitable at higher ratios, such as by high-intensity powdermixing, as in a Henschel mixer or a Waring powder blender, or by lowerintensity mixing techniques, as in a container on a roller or tumbler,may lead to variability in oxygen uptake, particularly when thecompositions are incorporated into thermoplastic resins and used in meltprocessing operations. Other things being equal, U.S. Pat. No. 5,744,056claims that oxygen-scavenging compositions prepared by slurry mixinghave the highest oxygen absorption efficiency or performance, followedin order by compositions prepared using high intensity solids mixers androller/tumbler mixing techniques.

U.S. Pat. No. 4,127,503 teaches the dissolution of an electrolyte inwater, contacting the solution with the oxidizable component (e.g. iron)and then removing the water from the composition. While this techniqueis suitable for salts which dissolve into water, it is not suitable forsalts which hydrolyze in the presence of a protic solvent, such aswater. Aluminum chloride for instance, will hydrolyze in the presence ofwater to hydrochloric acid and aluminum hydroxide.

Incorporation of dry blends into the wall of clear containers isdifficult because of the haze and colour brought on by the number ofdiscrete particles. United States Patent Applications 20030027912,20030040564, and 20030108702, teach that using larger oxidizableparticles minimizes the number of particles and improves the haze andcolour of the transparent wall of the container. As taught by thesepatent applications, the goal of oxygen scavenging compositions shouldbe to have as few particles as possible.

Another deficiency of using dry blended or ground conventionaloxidizable metal compositions is the growth of the particle as itoxidizes. It has been observed that as the particle oxidizes, theoxidized material blooms away from the particle making the particleappear larger over time and the colour shifts towards the colour of theoxidized metal. In the case of iron, the colour of the container wallshifts to yellow and yellow orange (rust).

Beverage or food containers presenting the above blooms are commerciallyunacceptable because the consumer incorrectly attributes the colour todeterioration of the product inside the container.

European Patent Application EP-1 506 718 titled Oxygen ScavengingCompositions and the Application thereof in Packaging Containers filedAug. 14, 2003 and World Patent Application WO-2005/016 762 titled“Oxygen-scavenging compositions and the application thereof in packagingand containers” submitted on Aug. 11, 2004 teaches that certain proticsolvent hydrolysable activating components can be placed onto theoxidizable component by dissolving the activating component into anessentially moisture free organic solution, contacting the solution withthe oxidizable metal then removing the solvent.

While the deposition of compounds from a liquid phase achieves thedesired intimacy of contact for a unitary particle, liquid phasedeposition presents several problems. First, there are the impurities ofthe solvent or reaction products of the salt with the solvent, oftencalled adducts. These may or may not be bound into the composition.Second, the liquid phase deposition requires a dissolution step and asolvent removal step.

A third drawback of liquid deposition is that the penetration of theliquid into the pores of many metal particles may be inhibited by thesurface tension of the liquid.

Yet, another deficiency of liquid deposition is the instability of theliquid deposited composition during further heat processing of thepolymer containing the liquid deposited oxygen scavenger. In the case ofpolyesters, it is advantageous to place the scavenger into the lowmolecular material and then subject the polymer to solid stateprocessing often at 225° C. for 16-20 hours. As discussed later, bottlesand preforms made from polymer containing a liquid deposited oxygenscavenger were unacceptably yellowed relative to the particles made fromthis invention.

Japanese Patent Application 09-237232 also describes depositing theactivating component from an aqueous or organic solution and placing itinto the wall of a container. The container wall of Japanese PublicationNumber 11-080555 (Patent Application 09-237232) is a laminate of metalfoil and plastic containing the oxygen scavenger lying between the foiland the package contents. The container is thus non-transparent and anyadvantage of reducing the number of scavenging particles is notappreciated.

Reacting the outer surface of the iron particle with a compound in avapour stream is another way to achieve intimate contact. JapanesePublication Number 11-302706 (Application Number 10-131379), titled“Iron Powder For Reactive Material and Its Production” teaches placingan enveloping layer containing 0.1-2% of the weight of chlorine in theiron powder which the enveloping layer which becomes a front face of[sic] ferric chloride by contacting hot chlorine or hydrogen chloridegas to iron powder. This way the ferric chloride is made to form in thefront face of said iron powder.

Although this vapour phase-solid phase reaction creates intimacy ofcontact, it limits one to the reaction products of iron and variousgasses. Because this particular Japanese disclosure requires that theoxidizing agent be a reaction product of iron, the practitioner islimited by the kinetics of the iron based salts and iron. Dissimilarmetals such as aluminum chloride and iron are not available with thistechnique.

U.S. Pat. No. 6,899,822 teaches the use of an acidifying electrolytesuch as sodium bisulfate in the presence of sodium chloride and iron.However, none of the examples teach depositing the materials onto theiron.

BRIEF SUMMARY OF THE INVENTION

This invention claims a process for manufacturing an oxygen scavengingparticle wherein the particle comprises at least one oxidizablecomponent and at least one activating component, and said processcomprises contacting the oxidizable component with a gas containing avapour of the activating component and depositing the activatingcomponent from the gas onto the oxidizable component in either a liquidor solid form.

The invention further discloses that the activating component maycontain a halide, in particular a metal halide. Further disclosed is theuse of a protic solvent hydrolysable halogen compound as the activatingcomponent. Specifically disclosed are AlCl₃, FeCl₂, FeCl₃, TiCl₄, POCl₃,SnCl₄, SOCl₂, n-Butyl SnCl₃, and AlBr₃ as protic solvent hydrolysablehalogens.

Also disclosed is that the oxidizable component comprise an oxidizablemetal or oxidizable metal alloy, preferably iron, aluminum, copper,zinc, manganese, magnesium and cobalt. It is further disclosed thatprior to the deposition of the activating component onto the oxidizablecomponent, the oxidizable component can be reduced from a higheroxidation state in a chamber selected from the group of the same chamberin which the oxidizable component is brought in contact with theactivating component and a chamber connected to the chamber in which theoxidizable component is brought in contact with the activatingcomponent.

Further disclosed is a process for manufacturing an oxygen scavengingparticle wherein the particle comprises at least one oxidizablecomponent and at least one activating component, and said processcomprises contacting the activating component with a gas containing avapour of the oxidizable component and depositing the oxidizablecomponent from the gas onto the activating component in either a liquidor solid form.

The product of this process can be incorporated into the wall of acontainer comprising a thermoplastic film-forming polymer in particularpolyethylene terephthalate and copolymers of polyethylene terephthalate.Also disclosed is the wall of a container made from the film formingpolymers such as a polyamide, polyethylene, or polypropylene wherein theparticles are incorporated into the film forming polymer.

DESCRIPTION OF THE DRAWING

FIG. 1 depicts a typical vapour deposition apparatus whereby the onecomponent is vaporized in one vessel called a vaporizer and thendeposited upon the other component in another vessel called thedeposition reactor.

DETAILED DESCRIPTION OF THE INVENTION

The deficiencies in the prior art can be eliminated according to theinvention by providing particles having high oxygen-scavengingefficiency in the presence of a protic solvent such as humidity orliquid phase water.

These particles comprise an oxidizable component, preferably anelemental metal such as of iron, cobalt, aluminum, copper, zinc,manganese, and magnesium, and at least one activating component; whereinone component has been deposited from the vapour phase onto the othercomponent. Implicitly, then to have the most utility, both componentsshould not boil or sublime at standard temperature and pressure.

It should be noted that while the examples deal with metals asoxidizable components, the invention is not limited to metals andelectrolytes, but any system where the components meet the criteriaoutlined below. The oxidizable component could be an organic whereby thecatalyst has be deposited from the vapour phase.

The role of the activating component is to promote or initiate thereaction of the oxidizable component with oxygen. In the absence of theactivating component, there is little or no reaction of the oxidizablecomponent with oxygen. The test therefore is whether the oxidizablecomponent reacts with more oxygen in the presence of the activatingcomponent than when the activating component is absent. In the case of atriggerable system, such as requiring those requiring water, the rate ofoxygen consumption of the composition comprising the activatingcomponent, the oxidizable component and water is compared with the rateof oxygen consumption of the oxidizable component and water.

For clarity, the activating component need not be the actual compoundthat participates in or catalyzes the reaction with oxygen, but mayparticipate in a reaction which produces a compound which doesparticipate in or catalyze the reaction with oxygen. While not to bebound by any mechanism, one hypothesis is that the aluminum chloridereacts with the water to form hydrochloric acid and it is thehydrochloric acid which actually sets up the galvanic cell. The otherhypothesis is that the hydrochloric acid reacts to form iron chloride,which is a known activator of the reaction of oxygen with oxidizablemetals.

It is therefore preferable that the activating component initiate thereaction of the oxidizable component in the presence of water. Thephrase initiate the reaction of the oxidizable component means that whenin the presence of water and the activating component, the oxidizablecomponent becomes more reactive with oxygen than it would be in thepresence of water without the activating component.

For a particle to be initiated by water contact, it is essential thatthis activating component promote or catalyze the reaction in thepresence of moisture. This promotion can be with or without theproduction of intermediate compounds. The moisture can come from directcontact with the liquid, absorption from the surrounding air or vapouror migration through another material. Requiring water is what makes thecomposition triggerable. In a typical application, the water will comefrom the packaged goods, such as beer or juice. When the composition isbound in the walls of a container, the water from the packaged goodsmigrates to the particle initiating the reaction of the particle withoxygen that passes from the outside of the wall to the inside.

To be triggerable, the activating component should be a water solubleelectrolyte, a water soluble acidifying electrolyte, a mixture of awater soluble electrolyte and acidifying agents, or a protic solventhydrolysable compound or react to form an acidifying electrolyte, amixture of a water soluble electrolyte and acidifying electrolyte. Ofthe protic solvent hydrolysable compounds, those with halogens such aschlorine and bromine are preferred. Again, the activating component is acomponent which increases the reaction rate of the oxidizable componentwith oxygen. Whether the activating component remains in the system isirrelevant.

The ability of the activating component to initiate the oxygenscavenging reaction depends upon the acidity and electrolytic strengthsof the activating component or products of the activating component'shydrolyzation. For example, it is believed that when sufficient watercontacts the AlCl₃/Iron particle, the AlCl₃ hydrolyzes to Al₂O₃ andhydrochloric acid. Hydrochloric acid is a strong acid and electrolytewhich promotes the rapid and efficient reaction of the iron with oxygen.

U.S. Pat. No. 5,885,481, the teachings of which are incorporated byreference herein, teaches the advantages of using a non-halogenatedacidifying electrolytic component.

Many protic solvent hydrolysable compounds such as titaniumtetrachloride, tin tetrachloride, and POCl₃, SOCl₂, SCl₂, S₂Cl₂, PCl₃,PSCl₃, PBr₃, POBr₃, PSBr₃, PCl₅, PBr₅, SiCl₄, GeCl₄, SbCl₅ are liquidsat room temperature and readily boil. Other protic solvent hydrolysablecompounds such as AlCl₃, FeCl₂, FeCl₃, AlBr₃, SbCl₃, SbBr₃, and ZrCl₄sublime at relatively low temperatures. Higher boiling compounds areZnCl₂, ZnBr₂ and FeBr₃.

Preferred protic solvent hydrolysable halogen compounds are the halides,in particular chloride and bromide, more preferably AlCl₃, AlBr₃, FeCl₂FeBr₂, TiCl₄, SnCl₄, and POCl₃.

A non-triggerable system can also be made using the vapour depositionprocess described in this invention. If non-triggerable, the activatingcomponent promotes the reaction of the oxidizable component with oxygenimmediately, or with very low amounts of moisture, (<70%, R.H.) uponcontact with the oxidizable component. See, for example U.S. Pat. No.6,133,361 noting metallic iodide and metallic bromide compounds areexamples of activating components that require very little moisture andare therefore non-triggerable activating components. Those metalliciodide and metallic bromide compounds which can be placed into thevapour phase are therefore contemplated with the claims of this process.

The vapour deposition process requires two quasi-unit operations. Thefirst unit operation, or step, is contacting the oxidizable componentwith the vapour phase of the activating component. The next unitoperation, or second step, is the vapour deposition wherein theactivating component is condensed or de-sublimed as a liquid or solidonto the oxidizable component. For clarity, this invention is notlimited to vapour depositing the activating component onto theoxidizable component. The invention is equally applicable to depositingthe oxidizable component onto the activating component if such weredesired.

While the following examples teach and emphasize the vapour depositionof the activating component onto the oxidizable component, theoxidizable component could be deposited from the vapour stream onto theactivating component. For example, iron penta-carbonyl, Fe(CO)₅,thermally decomposes into elemental iron. As it decomposes it moves fromthe vapour phase. If the thermal decomposition of carbonyl iron occurredover a bed of sodium chloride particles, the elemental iron would formaround the sodium chloride particles. In the proper ratios, the waterwould dissolve the sodium chloride away leaving a hollow iron sphere toreact with the oxygen.

Contacting the oxidizable component with the vapour phase activatingcomponent and condensing or de-subliming the activating component ontothe oxidizable component are not distinct or separate process stepsrequiring intervention or a time interval between them. These unitoperations can occur simultaneously. As described in the fourthembodiment, the vapour phase activating component will condense orde-sublime when it is brought in contact with a cooler oxidizablecomponent. Therefore, the contacting step refers to the step of placingthe vapour phase activating component in the same chamber as theoxidizable component so that the components are touching or in contactwith each other. The vapour deposition step refers to the actual phasechange that occurs when the vapour phase activating component goes froma gas to either a liquid or a solid. Some will say that when the hotvapour contacts the cold solid, the phase change is immediate. Thus,while the steps are listed sequentially, it is fully contemplated asdemonstrated in the examples, that the steps could well occur virtuallysimultaneously.

In general, the activating component is placed into a vapour stream byeither boiling, flashing or subliming the activating component bymanipulating temperature and/or pressure. The vaporized activatingcomponent is contacted with the oxidizable particles and once in contactwith the oxidizable particle, the activating component is deposited fromthe vapour stream onto the oxidizable component through condensation orde-sublimation.

The terms vapour deposition, deposited onto, deposited onto from avapour stream, deposited from a vapour stream, or deposition of thecomponent from a gas to either a liquid or solid on the oxidizablecomponent all refer to the condensation, de-sublimation, or theirequivalent, of the one component onto the other component; usually thedeposition of the activating component onto the oxidizable component. Byimplication, even when the word vapour is not present, the depositionoccurs from a vapour stream.

The deposition of the activating component on the oxidizable metal froma vapour stream intimately attaches the activating component with theoxidizable component and creates a discrete particle containing bothcomponents. These scavenging particles can then be mixed into a polymermatrix by any of the known techniques, such as dispersing the particlesinto polymer liquid via a liquid melt reactor, an extruder or evenduring the injection molding or extrusion of an article such as apreform, film or sheet.

The vapour deposition can be accomplished by contacting the gas phaseactivating component with the oxidizable component and condensing theactivating component onto the oxidizable component. The best results areachieved when the process is conducted in view of the followingobservations.

The process is best carried out in an oxygen and moisture freeenvironment. Also, because of the intimacy of contact, the requiredamount of activating component is substantially less than prior artindications. The desired ratio of activating component to oxidizablecomponent can readily be determined by trial and error without undueexperimentation. One makes particles according to the process, analyzesthe results and increases or decreases the amount of activatingcomponent to achieve the desired oxygen scavenging activity. Thescavenging function is not linear with the amount of activatingcomponent and at some point too much activating component can be used.

The oxidizable component could be several compounds, or alloys ofcompounds. Additionally, the activating component is also not limited tojust one compound. Additional agents such as binders and water absorberscan be placed on the oxidizable particle first and the particlesubjected to vapour deposition. For example, one could use a waterslurry to put sodium chloride onto iron particles and then vapourdeposit AlCl₃ onto the NaCl/Fe⁰ particle. Many variations becomeapparent in light of the following embodiments.

In the first embodiment, the vapour deposition is carried out in asingle chamber by placing the desired proportions of oxidizablecomponent and activating component into a chamber or vessel. The chamberand its contents are then heated to a sufficient temperature and/orexposed to sufficient vacuum to place the activating component into thevapour phase. In the case of aluminum chloride, the activating componentsublimes into the vapour phase. In the case of titanium tetrachloride,the activating component boils into the vapour phase. Pressure must bereduced for those compounds which decompose at high temperatures.

The vapour deposition (condensation or de-sublimation) of the vapourphase activating component onto the oxidizable component can beaccomplished by cooling and/or increasing the pressure so that theactivating component will transition from a vapour to either a liquid orsolid on the oxidizable component. The resulting oxygen scavengerparticles can then be incorporated into a polymer matrix which is thensubsequently formed into a container wall.

In a second embodiment, vapour deposition can be carried out by placingthe activating component into its gaseous state or vapour phase byheating and/or reducing the pressure surrounding the activatingcomponent. The stream of vapour phase activating component is thenplaced in contact with the oxidizable particles. The activatingcomponent can then be deposited from the vapour stream onto theoxidizable particles by cooling and/or increasing the pressure of thesystem.

In a third embodiment, the stream of vapour phase activating componentis placed in contact with a bed of oxidizable particles. It isadvantageous to fluidize the bed and use the stream of gaseous vapourphase activating component as the fluidizing media. Depending upon theamount of activating component, the vapour stream may need to besupplemented with an inert gas such as nitrogen to maintain fluidizednature of the bed.

FIG. 1 depicts the vapour deposition apparatus also used in Examples IV,Vb, Vc, and Vd. The vaporizer or sublimator, depicted by the label 1D,operates as a sublimator of AlCl₃, depicted as 1B. The vaporizer orsublimator, 1D, is attached to the deposition reactor, depicted by thelabel 1F. In FIG. 1, nitrogen (N₂) is introduced into thevaporizer/sublimator (1D), through the tube labelled 1C. The nitrogen isheated to the desired sublimation temperature as it passes through theheating media, preferably a sand bath, depicted by 1A.

In the case of AlCl₃, this temperature is approximately 235-250° C. Formaterials which boil instead of sublime, the temperature would be at orabove the respective boiling point. The pre-heated nitrogen passesthrough the AlCl₃ bed labelled 1B, fluidizing the AlCl₃ and carrying thenitrogen/AlCl₃ vapours through the heated tube labelled 1J. The heatingcoils and insulation of tube 1J are depicted as 1E. The nitrogen/AlCl₃vapour is introduced into the deposition reactor labelled 1F at the baseof the fluidized iron bed depicted as 1G, but above the distributionplate identified as 1K. The iron is fluidized by the fluidizing nitrogenintroduced into the deposition reactor labelled 1F through inlet tube1H. The nitrogen flows through holes in the distributor plate 1K. Thetemperature of the iron particles is substantially below thede-sublimation or condensation temperature of the AlCl₃. The coolingfrom the iron particles causes the AlCl₃ to condense or de-sublime fromthe vapour stream onto the fluidized iron particles. The nitrogen thenexits the deposition reactor at 1I. After the AlCl₃ is consumed anddeposited on the iron, the iron is removed from the deposition reactor1F.

The deposition of aluminum chloride on an oxidizable particle, such aselemental iron, is best carried out at as fast a rate as possible inorder to minimize the growth of large crystals of aluminum chlorideresulting in a more uniform coating of the particles. For the aluminumchloride/iron system, the sublimator should be operated at a temperaturebetween 225 and 250° C., preferably at 235-240° C. and the nitrogen usedto sweep the aluminum chloride vapours out of the sublimator should bepreheated to about this same temperature. Surprisingly, the aluminumchloride sublimation at a nitrogen linear velocity of 30 ft/min thru a 2inch diameter sublimator, at 250° C. was slower than the sublimation at235° C. This is believed to be a result of the aluminum chlorideclumping and reducing the effective surface area from which sublimationcan occur. The sublimation can be followed by measuring the temperatureof the sublimator at various points along its height. As sublimation ofthe aluminum chloride progresses, the temperature measured by a probe inthe reactor near the top approaches that of the heating bath. Withadditional sublimation time, a probe near the midpoint will approachthis temperature and eventually, a probe near the base also reaches theheating bath temperature. At the same time, the temperature of the metalbed where the aluminum chloride is being condensed will reach a maximumtemperature and then, as there is less and less aluminum chloride tosublime and recondense, approach room temperature.

Transfer lines to the vapour deposition reactor should be traced toprevent the vaporized component from condensing in the line. In the caseof aluminum chloride, the line temperature should be maintained at leastat 200° C., preferably at about 220° C. to avoid condensation of thealuminum chloride in the lines.

The velocity of nitrogen thru the fluidization reactor is dependent uponthe shape and size of the oxidizable particles powder and also thereactor design. This must be determined experimentally. An agitator wasalso fitted to the reactor to provide the most efficient mixing of theoxidizable particles and consequently optimize the uniformity of thevapour deposition.

Operation of a bed of particles is well known in the art and such bedmay be fluidized, fixed, horizontal, or vertical. The bed may be moving,as in a continuous operation or static, wherein the vapour isrecirculated through the bed until the desired amount of activatingcomponent is deposited upon the oxidizable component.

The deposition can comprise its own set of variations. In the preferredfourth embodiment the stream of vaporized activating component(s) isbrought in contact with a bed of cooler oxidizable particles. Thetemperatures of the activating component(s) and oxidizable component(s)are selected such that once the vapour stream contacts the oxidizablecomponent, the activating component(s) is immediately deposited from thevapour stream onto the colder oxidizable component(s). An alternativevariation is to pass the cooler oxidizable component(s) through thechamber containing the vaporized activating component(s).

One skilled in the art will recognize that a simple enthalpy balancewill determine the maximum allowable temperature of the solid oxidizablecomponent.

The temperature chosen must be below the respective vaporizationtemperature of the activating component at the deposition pressure,usually atmospheric. The following example demonstrates the math asapplied to an oxidizable metal. The initial temperature must thereforebe less than the vaporization temperature at the deposition pressureminus the amount of activating component times the heat of vaporizationof the activating component divided by the product of the amount ofoxidizable metal times the heat capacity of the solid metal.

[(Tv−Ts)×Cp _(ACg) Hv)]×AC≦(Tf−Ti)×(OC×Cp _(OCs))

Where, Tv=Temperature of the Activating Component in its Initial VaporPhase

Ts=Temperature at which the Activating Component Desublimes orCondenses.

Cp_(OCs)=Heat Capacity of the Oxidizable Component at DepositionConditions. Hv=Heat of DeSublimation or Condensation of the ActivatingComponent at Deposition Temperature and Pressure AC=Amount of ActivatingComponent Ti=Initial Temperature of the Oxidizable Component. Tf=FinalTemperature of the Oxidizable Component. OC=Amount of OxidizableComponent Cp_(OCs)=Heat Capacity of the Oxidizable Component atDeposition Conditions.

The maximum initial temperature will occur if the oxidizable componentfinal temperature reaches the deposition temperature (sublimation orboiling point). Therefore, Ts can be substituted for Tf and the balancecan be solved for the maximum Ti. Ti can therefore must be less than thevalue in the following equation.

Ti≦Ts−[((Tv−Ts)×Cp _(ACg) +Hv))×AC/(OC×Cp _(OCs))]

In practice, one will want to keep the initial temperature well belowthe vaporisation temperature.

After dispersion of the vapour deposited oxygen scavenging particle intothe polymer matrix, every polymer void or capsule containing a particlewith the oxidizable component will also contain an activating component.In contrast, when a dry blend of the activating and oxidizablecomponents is incorporated into the polymer matrix the separateparticles are often not in the same vicinity and the polymer separatingthe activating component from the oxidizable component creates a barrierthat renders the particle virtually ineffective as an oxygen scavenger.

The oxidizable particles preferably have an average particle size lessthan 50 μm. Iron is the preferred metal based upon cost. While theelectrolytic reduced unannealed or annealed iron is preferred, carbonyland carbon monoxide or hydrogen reduced sponge irons are also suitable.It should be noted that hydrogen and carbon monoxide reduced forms,known as sponge iron, are generally less reactive than the electrolyticreduced iron.

While iron is the preferred oxidizable component for cost reasons,cobalt, tin, aluminum, zinc, manganese and copper are all candidates forthe process of this invention.

It is also possible to reduce the oxidizable component immediately priorto the vapour deposition, thus creating an efficient batch or continuousproduction process starting from inexpensive oxidized raw materials. Forexample, the reduction of iron oxide to elemental iron is well known inthe art and can be done by passing hot hydrogen or carbon monoxide overthe metal. The hydrogen or carbon monoxide reacts with the oxygenleaving the reduced porous metal behind. In a batch process, thereduction would occur in the same chamber as the deposition. In acontinuous process, the reduction would occur in a separate chamber andthe reduced metal passed to a different chamber where the activatingcomponent would be deposited onto oxidizable metal.

Vapour deposition as used in this invention is also very effective whencreating nano-scale oxygen scavenging particles when compared to theconventional blending or slurry contacting techniques. Nano-size ironparticles are those particles with diameters less than 1 micron,preferably less than 500 nanometers, and more preferably less than 200nanometers.

The intimate contact of the activating component is essential fornano-scale particles in a fixed media such as a film or container wall.Dry blends of traditional scavenging compositions do not provide enoughactivating component in intimate contact with the nano-iron to beeffective in a fixed media.

The addition of the reduction step prior to vapour deposition isparticularly useful in treating nano-iron. Due to its pyrophoricity,nano-iron is often treated with organic oils or solvents so it can besafely shipped and handled. These solvents often reduce the reactivityof the nano-iron. However, fully oxidized iron (nano-rust) is readilyavailable in nano-scale and is used for pigments and paints.

This nano-rust can be placed into a reduction chamber and reduced tonano-iron. The nano-iron can then be transported to vapour depositionchamber where the vaporized activating component is then deposited fromthe vapour stream onto the nano-iron. In this fashion, the nano-oxygenscavenger can be made in a batch or continuous process starting fromnano-rust.

In another embodiment, the nano-rust can be reduced in the same chamberas the vapour deposition.

The oxidizable component, particularly the metals, does not need to be100% pure. Minor alloying elements such as nickel, chromium, silicon andother compounds can be present. Using iron as an example, the mixturesof iron with minor amounts of other metals can be used. The iron-basedcompositions are incorporated into the wall of a container made fromfilm-forming polymers, preferably aromatic polyester, in amounts from500 to 10000 parts by weight per million parts by weight polymer,preferably 1000 to 6000 parts per million parts polymer. In the case ofnano-scale scavengers, 200-2000 ppm may be sufficient. When used innon-transparent packaging, the amounts of scavenging composition can goas high as 5 weight percent of the total polymer—iron composition.

Of the film forming polymers, polyester is preferred. Suitablepolyesters include those produced from aromatic, aliphatic orcycloaliphatic dicarboxylic acids of from 4 to about 40 carbon atoms andaliphatic or alicyclic glycols having from 2 to about 24 carbon atoms.

Polyesters employed in the present invention can be prepared byconventional polymerization procedures well known in the art. Thepolyester polymers and copolymers may be prepared, for example, by meltphase polymerization involving the reaction of a diol with adicarboxylic acid, or its corresponding diester. Various copolymersresulting from use of multiple diols and diacids may also be used.Polymers containing repeating units of only one chemical composition arehomopolymers. Polymers with two or more chemically different repeatunits in the same macromolecule are termed copolymers. The diversity ofthe repeat units depends on the number of different types of monomerspresent in the initial polymerization reaction. In the case ofpolyesters, copolymers include reacting one or more diols with a diacidor multiple diacids, and are sometimes referred to as terpolymers.

As noted hereinabove, suitable dicarboxylic acids include thosecomprising from about 4 to about 40 carbon atoms. Specific dicarboxylicacids include, but are not limited to, terephthalic acid, isophthalicacid, naphthalene 2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid,1,3-phenylenedioxydiacetic acid, 1,2-phenylenedioxydiacetic acid,1,4-phenylenedioxydiacetic acid, succinic acid, glutaric acid, adipicacid, azelaic acid, sebacic acid, and the like. Specific esters include,but are not limited to, the various isomeric phthalic and naphthalicdiesters.

These acids or esters may be reacted with an aliphatic diol preferablyhaving from about 2 to about 24 carbon atoms, a cycloaliphatic diolhaving from about 7 to about 24 carbon atoms, an aromatic diol havingfrom about 6 to about 24 carbon atoms, or a glycol ether having from 4to 24 carbon atoms. Suitable diols include, but are not limited toethylene glycol, 1,4-butenediol, trimethylene glycol, 1,6-hexanediol,1,4-cyclohexanedimethanol, diethylene glycol, resorcinol ethoxy ethylether, and hydroquinone ethoxy ethyl ether.

Polyfunctional comonomers can also be used, typically in amounts of fromabout 0.1 to about 3 mole percent. Suitable comonomers include, but arenot limited to, trimellitic anhydride, trimethylolpropane, pyromelliticdianhydride (PMDA), and pentaerythritol. Polyester-forming polyacids orpolyols can also be used. Blends of polyesters and copolyesters may alsobe useful in the present invention.

One preferred polyester is polyethylene terephthalate (PET) formed fromthe approximate 1:1 stoichiometric reaction of terephthalic acid, or itsester, with ethylene glycol. Another preferred polyester is polyethylenenaphthalate (PEN) formed from the approximate 1:1 to 1:1.6stoichiometric reaction of naphthalene dicarboxylic acid, or its ester,with ethylene glycol. Another preferred polyester is polybutyleneterephthalate (PBT). Copolymers of PET, copolymers of PEN, andcopolymers of PBT are also preferred. Specific copolymers andterpolymers of interest are PET with combinations of isophthalic acid orits diester, 2,6 naphthalic acid or its diester, and/or cyclohexanedimethanol.

The esterification or polycondensation reaction of the carboxylic acidor ester with glycol typically takes place in the presence of acatalyst. Suitable catalysts include, but are not limited to, antimonyoxide, antimony triacetate, antimony ethylene glycolate,organomagnesium, tin oxide, titanium alkoxides, dibutyl tin dilaurate,and germanium oxide. These catalysts may be used in combination withzinc, manganese, or magnesium acetates or benzoates. Catalystscomprising antimony are preferred. Another preferred polyester ispolytrimethylene terephthalate (PTT). It can be prepared by, forexample, reacting 1,3-propanediol with at least one aromatic diacid oralkyl ester thereof. Preferred diacids and alkyl esters includeterephthalic acid (TPA) or dimethyl terephthalate (DMT). Accordingly,the PTT preferably comprises at least about 80 mole percent of eitherTPA or DMT. Other diols which may be copolymerized in such a polyesterinclude, for example, ethylene glycol, diethylene glycol,1,4-cyclohexane dimethanol, and 1,4-butanediol. Isophthalic acid andsebacic acid are an example of simultaneously using an aromatic andaliphatic acid to make a copolymer.

Preferred catalysts for preparing PTT include titanium and zirconiumcompounds. Suitable catalytic titanium compounds include, but are notlimited to, titanium alkylates and their derivatives, titanium complexsalts, titanium complexes with hydroxycarboxylic acids, titaniumdioxide-silicon dioxide-co-precipitates, and hydratedalkaline-containing titanium dioxide. Specific examples includetetra-(2-ethylhexyl)-titanate, tetrastearyl titanate,diisopropoxy-bis(acetyl-acetonato)-titanium,di-n-butoxy-bis(triethanolaminato)-titanium, tributylmonoacetyltitanate,triisopropyl monoacetyltitanate, tetrabenzoic acid titanate, alkalititanium oxalates and malonates, potassium hexafluorotitanate, andtitanium complexes with tartaric acid, citric acid or lactic acid.Preferred catalytic titanium compounds are titanium tetrabutylate andtitanium tetraisopropylate. The corresponding zirconium compounds mayalso be used.

The polymer using this invention may also contain small amounts ofphosphorous compounds, such as phosphates, and a catalyst such as acobalt compound, that tends to impart a blue hue. Also, small amounts ofother polymers such as polyolefins can be tolerated in the continuousmatrix.

The melt phase polymerization described above may be followed by acrystallization step, then a solid phase polymerization (SSP) step toachieve the intrinsic viscosity necessary for the manufacture of certainarticles such as bottles. The crystallization and polymerization can beperformed in a tumbler dryer reaction in a batch-type system.

In many cases, it is advantageous to incorporate the scavengerimmediately following the melt polymerization step and subjecting thepolymer containing the scavenger to the solid phase polymerization. Thevapour deposition process of this invention creates particles which donot substantially degrade or colour the polymer during the solid phasepolymerization. In contrast, the product from the organic liquiddeposition process does cause discoloration. This is believed to comefrom the tramp organic or adducts which are attached to the particle.

Alternatively, the crystallization and polymerization can beaccomplished in a continuous solid state process whereby the polymerflows from one vessel to another after its predetermined treatment ineach vessel. The crystallization conditions preferably include atemperature of from about 100° C. to about 150° C. The solid phasepolymerization conditions preferably include a temperature of from about200° C. to about 232° C., and more preferably from about 215° C. toabout 232° C. The solid phase polymerization may be carried out for atime sufficient to raise the intrinsic viscosity to the desired level,which will depend upon the application. For a typical bottleapplication, the preferred intrinsic viscosity is from about 0.65 toabout 1.0 deciliter/gram, as determined by ASTM D-4603-86 at 30° C. in a60/40 by weight mixture of phenol and tetrachloroethane. The timerequired to reach this viscosity may range from about 8 to about 21hours.

However, one could use a film forming polyester of at least 0.45 dl/g,an intermediate feed I.V. of 0.49 to 0.59 dl/g, or more preferably 0.52to 0.56 dl/g. The polymer could also be a polyester bottle resin of feedI.V. ranging from 0.59 to 0.69 dl/g, more preferably 0.61 to 0.64 dl/g,with a typical I.V. for bottles ranging from 0.72 to 0.84 dl/g, morepreferably 0.74 to 0.82 dl/g. For packaging trays the typical I.V.ranges from 0.80 to 1.50 dl/g, more preferably from 0.89 to 0.95 dl/g.It is noted that while the measured I.V. of a polymer is a single value,that value represents the composite of the various molecule chainlengths.

In one embodiment of the invention, the article-forming polyester of thepresent invention may comprise recycled polyester or materials derivedfrom recycled polyester, such as polyester monomers, catalysts, andoligomers. Examples of other film-forming polymers include polyamides,polycarbonate, PVC and polyolefins such as polyethylene andpolypropylene.

The oxygen-scavenging compositions can be added directly to thethermoplastic polymer compounding or melt-fabrication operation, such asthe extrusion section thereof, after which the molten mixture can beadvanced directly to the article-fabrication line.

Alternatively, the compositions can be compounded into masterbatchconcentrate pellets, which can be further incorporated into packagingpolymers for further processing into the desired article.

The concentrates in polyester resins preferably contain more than 20parts of oxygen-scavenging composition per hundred parts of resin, butpreferably between 5 and 10 parts per hundred. Containers having atleast one wall incorporating the oxygen-scavengers of the presentinvention are the preferred articles. Cups, pouches, boxes, bottles,lids and wrapped films are also examples of such walls. Stretched andunstretched films are included in the definition of container walls.

It is also contemplated to provide articles, with both active andpassive oxygen barrier properties through use of one or more passive gasbarrier layers in conjunction with one or more layers according to theinvention. Alternatively, the passive barrier and oxygen scavengingcomposition may both be in the same layer.

Thus for products calling for long shelf-life, an oxygen scavenginglayer according the present invention can be used in conjunction with apassive gas barrier layer.

Another advantage of the claimed particles and of the polymers andmanufactured articles into which they are incorporated is their storagestability i.e. their lack of reactivity in the absence of humidity,which permits long storage periods before filling.

As mentioned, the containers having at least a light transmitting wallcomprising the oxygen-scavenging compositions of the present invention,advantageously possess both high scavenging efficiency and the uniqueproperty of the reduced bloom of the particle upon reacting with oxygenin presence of humidity. The reduced bloom size also occurs incontainers having haze values falling within a commercially acceptablerange.

Many polymers are transparent, but polymers that are transparent tovisible light may become opaque, as the result of the presence ofadditives such as fillers, scavengers, stabilizers, and similaradditives. The opacity results from light-scattering occurring withinthe material.

Haze is the measure of the amount of light deviation from the directionof transmittance by at least 2.5 degrees.

The colour and brightness of a polyester article can be observedvisually, and can also be quantitatively determined by a HunterLab ColorQuest Spectrometer. This instrument uses the 1976 CIE, a*, b* and L*designation of colour and brightness. An a* coordinate defines a colouraxis wherein plus values are toward the red end of the colour spectrumand minus values are toward the green end.

The b* coordinate defines a second colour axis, wherein plus values aretoward the yellow end and minus values are toward the blue end.

Higher L* values indicate enhanced brightness of the material.

As indicated, the containers comprising at least one wall incorporatingthe oxygen scavengers of the present invention do not present as large abloom as do conventional scavengers upon aging.

The microscope observation of the wall upon aging shows a limited numberof black dots uniformly distributed within the wall; the wall areaoccupied by the dots is a small fraction of the total area. By contrast,the wall of the containers incorporating prior art oxygen-scavengersshow marked visual dots due to the formation of large blooms distributedalong the wall. Conventional scavengers also show a yellow/orangecoloration. The compositions listed in the examples showed a darkeningof the container wall, but no yellow/orange shift in colour.

The colour parameters of the wall of the containers of the presentinvention show a small decrease of the minus a* values and plus b*values referred to the a* and b* values of the wall not containingscavengers, whereas the walls incorporating prior art scavengers showplus a* values and increased plus b* values.

Preferred wall-containers are stretched bottles with a thickness fromabout 280 to 410 μm and haze values of about 1% or less per milthickness. Note that all bottle sidewalls used in the examples fallwithin the thickness noted.

The following examples are provided for purpose of illustrating themanufacture of the composition and the composition properties and arenot intended to limit the scope of the invention.

While the best mode and preferred embodiment of the invention have beenset forth in accord with the Patent Statutes, the scope of thisinvention is not limited thereto, but rather is defined by the attachedclaims. Thus, the scope of the invention includes all modifications andvariations that may fall within the scope of the claims

Standard Evaluation Procedure

Each series of scavenging particles was evaluated for oxygen scavengingand bottle aesthetics as follows:

Unless otherwise indicated, the scavenging particles were dispersed intothe polymer matrix of either 52 or 27 gram preforms by mixing 6 gms ofthe oxygen scavenging particles with 1994 gms of a commerciallyavailable PET co-polyester (8006S supplied by M&G Polymers USA, LLC)which had been previously dried overnight in a vacuum oven at 150° C. ina can. The physical mixture was then charged to an injection moldingmachine which melted the polymer and dispersed the particles into thepreforms. The preforms were blown into either 2 Liter or 600 ml,bottles, respectively, after they had aged for one day. In the case ofthe nano-scale scavenging particles, 1000 ppm of the scavengingparticles were added to the polymer.

Panels were cut from the walls of the bottles and analyzed for oxygenscavenging capability using the accelerated oxygen scavenging testmethod described in the methods section. The oxygen data is listed inTable I and demonstrates the high degree of scavenging and thetriggerable nature of the scavenger. Table II lists the bottleaesthetics of haze, L*, a*, and b*.

Example I Fe⁰/10% FeCl₃ in Sealed Vessel

A 50 ml Erlenmeyer flask with a screw cap was dried at 150° C. undernitrogen (nitrogen) and cooled to room temperature. The flask was thencharged with the activating component (5.42 gms or 0.033 moles ofanhydrous FeCl₃ obtained from Aldrich Chemical Company) and 55.8 gms(1.0 moles) of oxidizable component (reduced sponge iron powder fromNorth American Hoganas, grade XCS 50). The FeCl₃ (boiling point of 316°C., vaporization temperature of 300° C.) was converted to a gas andbrought in contact with reduced iron by placing the capped flask in a300° C. fluidized sand bath overnight. The FeCl₃ was deposited onto theiron by cooling the flask under nitrogen. The resulting particles werebroken up and crushed into finer particles. The oxygen scavengingparticles contained 3.28 weight percent chloride.

The oxygen scavenging analysis showed that there was little reactivityunder dry conditions, but a high degree of reactivity when wet. Thisindicated the system was highly reactive and also triggerable.

Example II Fe⁰/FeCl₃ in a Fluidized Bed

A tubular fluidized bed deposition reactor was charged with 5.45 Kgs of−38/+20 micron sized electrolytically reduced iron metal powder (gradeEA-230, available from OMG, now North American Hoganas). The −38/+20sieve cut was obtained by screening the powder through 38 micron and 20micron Tyler screens and recovering the part on top of the 20 micronscreen. The iron powder bed was fluidized by passing a sufficient rateof nitrogen through a nitrogen distributor plate and through the bed.

The FeCl₃ (Aldrich, USA) was vaporized into the gas phase in a secondreaction vessel called a vaporizer or sublimator. 26 gms of FeCl₃(nominally 0.5 w/w % FeCl₃) was placed in the vaporizer which wasenclosed in a 300° C. sand bath. The FeCl₃ was conveyed to the fluidizedbed by passing nitrogen over the top of the FeCl₃, taking the nitrogencontaining the FeCl₃ vapours from the top of the reactor and piping itthrough a traced, insulated transfer line to the tubular fluidized bedreactor containing the fluidized iron metal powder. The vaporized FeCl₃was contacted with the iron by introducing the FeCl₃ just above thenitrogen distributor plate of the tubular reactor.

After the FeCl₃ in the vaporizer reached 300° C., the temperature of thesand bath was increased to 340° C. over 1 hr. Over the next two hoursthe vaporizer was held at 340° C. during which time the temperature ofthe iron increased to 56° C. This increased iron temperature indicatesdeposition of FeCl₃ on the colder iron due to the latent heat ofvaporization released during the phase change from vapour to solid.After two hours, the heat and nitrogen to the vaporizer were shut off,the fluidized iron then cooled to below 45° C. and discharged. Onopening the vaporizer, 1 gm of an orange-red solid (presumably Fe₂O₃)remained.

Again, the reactivity is quite high, particularly considering there wasonly 0.5 w/w % FeCl₃ versus Example I which had nominally 10 w/w % FeCl₃on the iron.

Example III Fe/AlCl₃ in a Sealed Vessel

A 50 ml Erlenmeyer flask with a screw cap was dried at 150° C. andcooled to room temperature. 2.5 gms (0.019 mol) of anhydrous AlCl₃(Aldrich, sublimation temperature 178° C.) and 100 gms (1.8 mol) reduced−20 micron iron powder were placed into the flask. The −20 micron powderwas obtained by sieving grade EA-230 electrolytically reduced iron metalpowder (available from OMG, now North American Hoganas). The flaskcontaining the AlCl₃ and iron was capped and shaken to mix theingredients. The AlCl₃ was vaporized and brought in contact with theiron by placing the flask in a fluidized sand bath at 175° C. for 3 hrs,removing the flask every 30-60 minutes to break up the looselyagglomerated mass. The AlCl₃ was deposited onto the iron by cooling theflask to room temperature under nitrogen. The resulting particles werebroken up and crushed. Analysis showed 2.02% total chloride on theparticles.

In this evaluation 4 gms of particles were dispersed into 1996 gmscopolyester and the resulting bottle was a heat set panelled bottle.Bottles were also compounded with 2000 ppm of the particles and 5% MXD66001 Nylon from Mitsubishi Gas Chemical. No accelerated oxygen test wasrun on these bottles.

Example IV Fe/5% AlCl₃ in a fluidized bed

The tubular fluidized bed reactor of Example II was charged with 5.45Kgs of EA-230 electrolytic iron powder (available from OMG, now NorthAmerican Hoganas, USA) sieved to −20 micron. The vaporizer of Example IIcontained 272.6 gms AlCl₃ (Aldrich, USA) and was placed in a sand bathat 225° C. Unlike Example II, hot nitrogen was passed through the AlCl₃gas, taken out the top of the vaporizer and piped thru a traced,insulated transfer line to the tubular fluidized bed reactor containingthe fluidized iron. The gaseous stream of AlCl₃ was brought in contactwith the iron by introducing the gas into the tubular reactor just abovethe nitrogen distributor plate. The process was carried out for 15minutes past the time at which the temperature immediately above thedistributor plate in the vaporizer reached that of the top of thevaporizer. The deposition of the AlCl₃ on the iron was evident as thetemperature of the iron increased to 57° C. The heat and nitrogen to thevaporizer were then turned off and the materials in the fluidized bedbegan to cool. When the iron cooled to below 45° C. it was discharged.On opening the vaporizer, essentially no AlCl₃ remained. Further, noevidence of AlCl₃ was observed on the upper part of the iron containingreactor.

Example Va “230 nm” Nano-Fe/2% AlCl₃ in a Fluidized Bed

The reduction of the nano-iron was accomplished by placing 3.1 Kg offerric oxide (R 1299, measuring 230 nanometer diameter prior toreduction, available from Elementis Pigments, East Saint Louis, Ill.,USA) into a the tubular fluidized bed reactor of Example II. The reactorwas placed in a sand bath and heated while nitrogen was passed into thebase of the reactor at a rate sufficient to fluidize the bed. When thereactor reached a temperature of 450° C., the gas flow was switched fromnitrogen to hydrogen. Hydrogen was passed through the reactor for 1 hr,holding the temperature at about 500-510° C. The hydrogen was thenreplaced with nitrogen, and the reactor removed from the sand bath andallowed to cool unopened overnight.

43 gms of AlCl₃ (Aldrich) was placed into the vaporizer of Example IIand in a sand bath at 225° C. Hot nitrogen was passed over the top ofthe AlCl₃, taken back out the top of the reactor, piped through atraced, insulated transfer line to the tubular reactor containing thefluidized reduced nano-iron. The AlCl₃ was brought in contact with theiron by introducing the AlCl₃ into the tubular reactor at a point justabove the nitrogen distributor plate. The iron temperature increasedindicating the deposition of the AlCl₃. The process continued for 30minutes after the temperatures in the vaporizer reached that of the sandbath. Heat and nitrogen to the vaporizer was then shut off and the ironcooled to below 45° C. The product was coated with about 500 ml mineraloil and discharged. On opening the vaporizer, 11 gm of AlCl₃ remained.

Example Vb “10×100 nm” Nano-Fe/10% AlCl₃ in a Fluidized Bed

1.95 Kg of ferric oxide (AC-1022 from Johnson Matthey, JacksonvilleFla., USA) was reduced in the same manner as Example Va. Aluminumchloride (AlCl₃) (Aldrich, 136 g) was vaporized by passing hot nitrogenthru the bed of AlCl₃ which was contained in a tubular reactor immersedin a sand bath at 225° C. The nitrogen containing AlCl₃ was then takenout the top of the reactor and brought in contact with the iron byintroducing the AlCl₃ into the iron containing tubular reactor at apoint just above the nitrogen distributor plate. The iron temperatureincreased indicating the deposition of the AlCl₃. The process continuedfor 30 minutes after the temperatures in the vaporizer reached that ofthe sand bath. Heat and nitrogen to the vaporizer was then shut off andthe iron cooled to below 45° C. The product was pyrophoric so two 8 ozjars were filled with dry powder under nitrogen and sealed. Degassedmineral spirits (1.5 L) was added and the resulting slurry discharged.Essentially no AlCl₃ was observed in the vaporizer.

Example Vc “10×100 nm” Nano-Fe⁰/20% AlCl₃ in a Fluidized Bed

The process of Example Vb was repeated using 272 g AlCl₃. The productdid not test as being pyrophoric but was treated as Example Vb as aprecaution.

Example Vd “80 nm” Nano-Fe⁰/10% AlCl₃ in a Fluidized Bed

Ferric Oxide (ColorTherm Red 110M from Bayer), 1.96 kg was reduced inthe manner outlined in Example Va.

AlCl₃ (Aldrich), 136 g was then vapour deposited on the reducedColorTherm Red 110M in the same manner as described in Vb.

Example VIa Blended Fe⁰/AlCl₃ Comparison

Under a nitrogen atmosphere, aluminium chloride powder was addeddirectly to electrolytic iron powder at 2.5% and 10% weight based on theweight of iron and blended for two hours at room temperature on a rollermill. These are labelled VIa and VIb, respectively. 2 Liter bottles weremade and sidewalls properties measured. The Hunter haze for the 10%blend at 3000 ppm iron was 53% and well above any commerciallyacceptable criteria for a transparent bottle.

Example VIc Comparison

A dry blend of 3000 ppm weight iron of Freshblend™ Scavenger fromMultisorb Technologies, Buffalo, N.Y. USA was injection molded with PETinto a 52.5 gram preform and made into a bottle (See “MultipleFunctionality Sorbents”, Calvo, William D. Proceedings of ACTIVEPackConference, p9 (2003) (announcing the commercialisation of Freshblend™for polyester). The sidewall was subjected to the accelerated oxygenabsorbance test (0.11 cm³ O₂/g polymer/1000 ppm Fe). While thecompositions had comparable oxygen scavenger absorbance, size of theblooms is significantly smaller for Example I, the subject of thecurrent invention.

Examples VId and VIe Other Blend Comparisons

Compositions were made blending iron and NaCl (8 w/w % weight based onweight of iron) and blending iron and NaHSO₄ (10 w/w % based on weightof iron as described in U.S. Pat. No. 5,885,481). These blends wereprepared by adding the appropriate salt directly into the iron powderand then mechanically blending of the mixture in a rotary mill. Thesetwo compositions are labelled VId and VIe respectively and wereconverted into 2 Liter bottles containing 4000 ppm of either blend.

Examples VII Suitability for Solid State Polymerization

This series demonstrates the improvement of the vapour deposition overthe deposition from an organic solution. The vapour deposited material(VIIa vs VIIb) does not exhibit the colour shift exhibited by theorganic deposited scavenger (VIIc vs VIId), in particular after heattreatment such as solid phase polymerization. VIIa and VIIb were blowninto 0.51 bottles, while VIIc and VIId were blown into 2 Liter Bottles.Thus the comparison is the change in colour within the same bottle.

Example VIIa is the bottle from Example IV. It is carried hereseparately for clarity of comparison.

In Example VIIb, 3000 ppm of the iron of Example IV was compounded viatwin screw extruder into the feed resin (nominal Intrinsic Viscosity of0.49) of Cleartuf® 8006S Available from M&G Polymers, USA. The feedresin was then crystallized and polymerized in its solid phase undervacuum until the IV reached 0.84. The material was then blown intobottles using the procedures described earlier.

In Example VIIc, bottles were made using 3000 ppm of scavenger preparedby depositing the AlCl₃ from an organic solution on iron as taught inExample 1 of European Patent Application 03425549.7 titled OxygenScavenging Compositions and the Application thereof in PackagingContainers filed Aug. 14, 2003, incorporated by reference.

In Example VIId, 3000 ppm of scavenger from Example VIIc was compoundedinto polyester, solid phase polymerized, and made into bottles similarto Example VIIb.

TABLE I Oxygen Scavenging Performance Wet Reactivity Days (cc02 per ofDry Wet gram ageing Reactivity Reactivity polymer per in (ccO2 per (ccO2per 1000 ppm G.C. gram gram Scavenging Ex. Description vial polymer)polymer) composition I Fe⁰/FeCl₃ in sealed vessel 1 0.028 0.009 4 0.1020.034 II Fe⁰/0.5% FeCl₃ in a 1 0.02 0.007 fluidized bed, 3000 ppm in 30.05 0.017 PET 10 0.08 0.027 IV Fe⁰/5% AlCl₃ in a fluidized 1 0.004 0.060.02 bed 4 0.016 0.18 0.06 10 0.020 0.28 0.093 Va “230 nm” Nano-Fe⁰/2.0%1 0.005 0.02 0.02 AlCl₃ in a fluidized bed 3 0.007 0.02 0.02 10 0.0140.04 0.04 Vb “10 × 100 nm” Nano-Fe⁰/10% 1 0.016 0.037 0.037 AlCl₃ in afluidized bed, 3 0.021 0.054 0.054 1000 ppm 5 0.016 0.065 0.065 Vc “10 ×100 nm” Nano-Fe⁰/20% 1 0.008 0.030 0.030 AlCl₃ in a fluidized bed, 30.011 0.047 0.047 1000 ppm 5 0.007 0.046 0.046 Vd 80 nm Nano-Fe⁰/10%AlCl₃ 1 0.0144 0.027 0.027 in a fluidized bed, 1000 ppm 3 0.017 0.0320.032 5 0.011 0.031 0.031 VIa 2.5 wt % AlCl₃ Dry Blend, 3 0.07 0.0233000 ppm in PET VIc 3000 ppm Freshblend ™ in 1 0.07 0.023 PET 3 0.160.053 10 0.34 0.113 VId 8 Wt % NaCl on Fe, blended 10 0.19 0.0475 at4000 ppm in PET VIe 10 Wt % NaHSO₄ on Fe, 10 0.34 0.085 blended at 4000ppm in PET

TABLE II Bottle Data Hunter Haze Example Fe Composition (%) L* a* b* VIa2.5 wt % AlCl₃ Dry Blend, 19.84 3000 ppm in PET VIIa Fe⁰/5% AlCl₃ in afluidized 21 77.15 −0.07 2.29 bed (3000 ppm) in PET VIIb Fe⁰/5% AlCl₃ ina fluidized 77.13 −0.11 2.93 bed after SSP VIIc 2.5 wt % AlCl₃ -Ethanol, 15.69 84.37 0.03 3.26 3000 ppm in PET, mixed at injectionmachine VIId 2.5 wt % AlCl₃ - Ethanol, 18.27 83.58 −0.13 3.26 3000 ppmin PET after SSP

Analytical Procedures Accelerated Oxygen Absorbance Test—Polymer Samples

Bottle sidewall samples of the iron-containing compositions are cut to apredetermined size with a template and the sidewall sample weights arerecorded to the nearest 0.01 g. The samples are placed into 20 ml gaschromatograph vials. The vials are either analysed dry or withactivation. Activated (wet) samples are activated by placing 2 ml ofaqueous 0.001 M acetic acid into the vial prior to being crimp sealed.The sidewall samples are stored at 50° C. The individual vials areanalysed by gas chromatography for consumption of oxygen vs. a controlat the prescribed time interval.

Intrinsic Viscosity

The intrinsic viscosity of intermediate molecular weight and lowcrystalline poly(ethylene terephthalate) and related polymers which aresoluble in 60/40 phenol/tetrachloroethane was determined by dissolving0.1 grams of polymer or ground pellet into 25 ml of 60/40phenol/tetrachloroethane solution and determining the viscosity of thesolution at 30° C.+/−0.05 relative to the solvent at the sametemperature using a Ubbelohde 1B viscometer. The intrinsic viscosity iscalculated using the Billmeyer equation based upon the relativeviscosity.

The intrinsic viscosity of high molecular weight or highly crystallinepoly(ethylene terephthalate) and related polymers which are not solublein phenol/tetrachloroethane was determined by dissolving 0.1 grams ofpolymer or ground pellet into 25 ml of 50/50 trifluoroaceticAcid/Dichloromethane and determining the viscosity of the solution at30° C.+/−0.05 relative to the solvent at the same temperature using aType OC Ubbelohde viscometer. The intrinsic viscosity is calculatedusing the Billmeyer equation and converted using a linear regression toobtain results which are consistent with those obtained using 60/40phenol/tetrachloroethane solvent. The linear regression is

IV in 60/40 phenol/tetrachloroethane=0.8229×IV in 50/50 trifluoroaceticAcid/Dichloromethane+0.0124

The Hunter Haze Measurement

The measurements were taken through the bottle side-walls. A HunterLabColorQUEST Sphere Spectrophotometer System equipped with an IBM PS/2Model 50Z computer, IBM Proprinter II dot matrix printer, assortedspecimen holders, and green, gray and white calibration tiles, and lighttrap was used. The HunterLab Spectrocolorimeter integrating spheresensor is a colour and appearance measurement instrument. Light from thelamp is diffused by the integrating sphere and passed either through(transmitted) or reflected (reflectance) off an object to a lens. Thelens collects the light and directs it to a diffraction grating thatdisperses it into its component wave lengths. The dispersed light isreflected onto a silicon diode array. Signals from the diodes passthrough an amplifier to a converter and are manipulated to produce thedata. Haze data is provided by the software. It is the calculated ratioof the diffuse light transmittance to the total light transmittancemultiplied by 100 to yield a “Haze %” (0% being a transparent material,and 100% being an opaque material). Samples prepared for eithertransmittance or reflectance must be clean and free of any surfacescratches or abrasion. The size of the sample must be consistent withthe geometry of the sphere opening and in the case of transmittance; thesample size is limited by the compartment dimension. Each sample istested in four different places, for example on the bottle sidewall orrepresentative film area.

A Panametrics Magna-Mike 8000 Hall Effect Thickness Gauge was employedto measure the bottle sidewall thickness.

1. A process for manufacturing an oxygen scavenging particle wherein the particle comprises at least one oxidizable component and at least one activating component, and said process comprises contacting the oxidizable component with a gas containing a vapour of the activating component and depositing the activating component from the gas onto the oxidizable component in either a liquid or solid form wherein the activating component comprises at least one compound selected from the group consisting of FeCl₂ and FeCl₃.
 2. The process according to claim 1 wherein the oxidizable component comprises at least one compound selected from the group consisting of an oxidizable metal and oxidizable metal alloy.
 3. The process according to claim 1 wherein the oxidizable component comprises an oxidizable metal selected from the group consisting of iron, aluminum, copper, zinc, manganese, and magnesium.
 4. The process according to claim 1, wherein the oxidizable component comprises iron.
 5. The process according to claim 1, wherein the oxidizable component comprises aluminum.
 6. The process according to claim 1 wherein the oxidized form of the oxidizable component is reduced from a higher oxidation state in a chamber selected from the group consisting of the same chamber in which the oxidizable component is brought in contact with the activating component and a chamber connected to the chamber in which the oxidizable component is brought in contact with the activating component.
 7. The process according to claim 6 wherein the oxidizable component comprises at least one compound selected from the group consisting of an oxidizable metal and metal alloy wherein at least one metal is selected from the group consisting of iron, aluminum, copper, zinc, manganese, and magnesium.
 8. The process according to claim 6, wherein the oxidizable component comprises iron.
 9. The process according to claim 6, wherein the oxidizable component comprises aluminum. 